2,066 research outputs found

    Magnesium Isotopes in Halo Stars

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    We have determined Mg isotope ratios in halo field dwarfs and giants in the globular cluster M71 based on high S/N high spectral resolution (R = 105^5) Keck HIRES spectra. Unlike previous claims of an important contribution from intermediate-mass AGB stars to the Galactic halo, we find that our 26^{26}Mg/24^{24}Mg ratios can be explained by massive stars.Comment: Proceedings, First Stars III, July 16-20, 2007, Santa F

    Innovation and Foreign Investment Behavior of the U.S. Pharmaceutical Industry

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    This paper deals with the links between the development of new drugs, and particularly of innovative new drugs, and the international activities of U.S. drug companies. While U.S. drug companies have developed new production processes - the most notable being the fermentation process for making penicillin - we concentrate in this paper on new products. Since production costs comprise less than 40 percent of the selling price of drugs and since the person choosing the drug rarely pays for it, growth in company sales and profits comes more from introducing new products than from cutting costs and prices of old products. The main novelty of our study is our examination of "innovative" as contrasted with "imitative" new drugs. Previous studies have generally focused on the total number of new drugs produced each year, but since our interest is in the causes and consequences of innovation, we have concentrated on the products we have rated as innovative. Section I explains our criteria for this distinction and presents our enumeration of the innovative new drugs for each of the 22 companies in our sample. In Section II we discuss trends in the rate of drug innovation and the factors influencing those trends. Section III describes our sample of drug companies and characterizes them with respect to their size, research investment, and innovativeness. Section IV examines the relation of innovativeness to the foreign activities of individual firms. In Section V we analyze, for a sample of 7 new drugs introduced by two companies, the rate at which use of the drugs was diffused among various countries arid the impact of the presence of manufacturing plants on the rate of diffusion.

    Outer Versus Inner Halo Globular Clusters: NGC 7492 Abundances

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    We have carried out a detailed abundance analysis for 21 elements in a sample of four RGB stars in the outer halo globular cluster NGC 7492 (R_(GC) 25 kpc); we find [Fe/H] = -1.82 dex inferred from Fe Ilines (-1.79 from Fe II) using high-dispersion (R = λ/Δλ = 35,000) spectra obtained with HIRES at the Keck Observatory. Most elements show no sign of star-to-star variation within our limited sample. We have, however, detected an anticorrelation between O and Na abundances similar to that seen in our previous analyses of inner halo GCs as well as in studies of relatively nearby GCs by others. We compare the abundance ratios in NGC 7492 with those we previously determined for the much closer old halo GCs M3 and M13. After making corrections for trends of abundance ratio with metallicity characteristic of halo stars, we find that for these three GCs, for each of the elements in common we deduce identical abundance ratios with respect to Fe to within the probable measurement uncertainties. Thus, the chemical history of the outer halo as exemplified by the metal-poor outer halo globular cluster NGC 7492 is indistinguishable from that of the inner halo, exemplified by M3 and M13, at least through the epoch of formation of these old globular clusters. This applies to the neutron capture processes as well

    An entity-relationship model of the flow of waste and resources in city-regions: Improving knowledge management for the circular economy

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    Waste and resources management is one of the domains where urban and regional planning can transition towards a Circular Economy, thus slowing environmental degradation. Improving waste and resources management in cities requires an adequate understanding of multiple systems and how they interact. New technologies contribute to improve waste management and resource efficiency, but knowledge silos hinder the possibility of delivering sound holistic solutions. Furthermore, lack of compatibility between data formats and diverse definitions of the same concept reduces information exchange across different urban domains. This paper addresses the challenge of organising and standardising information about waste and resources management in city regions. Given the amount and variety of data constantly captured, data models and standards are a crucial element of Industry 4.0. The paper proposes an Entity-Relationship Model to harmonise definitions and integrate information on waste and resources management. Furthermore, it helps to formalise the components of the system and their relationships. Semi-structured interviews with government officials, mobile app developers and academics provided insights into the specific system and endorsed the model. Finally, the paper illustrates the translation of the ERM into a relational database schema and instantiates Waste Management and industrial Symbiosis cases in Buenos Aires (ARG) and Helsingborg (SWE) to validate its general applicability. The data model for the Circular Flow of Waste and Resources presented here enhances traditional waste management perspectives by introducing Circular Economy strategies and spatial variables in the model. Thus, this research represents a step towards unlocking the true potential of Industry 4.0

    Mapping the spatial distribution of the effects of urban traffic congestion: methodological exploration using web based services

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    Sustainable transport systems are a necessary requirement to achieve efficient economic performance, enhance urban quality of life and diminish environmental costs.Congestion, a negative externality of mobility, is responsible for urban pollution, inefficiency and has adverse effects over individuals facing this problem. For these reasons, transport and city planning agencies have developed interests in deffining and measuring transportation congestion.Although, dfferent dffinitions and metrics have been used, congestion measurements are foundaggregated at a city level or for particular road segments. This study proposes a methodology that produces information from a web traffic service to map traffic congestion within an urbanarea. The method is simple and generalizable enough to be adopted in different urban areas.This paper presents the analysis of four European cities (Amsertdam, Glasgow, Goteborg and Lisbon) and show that the conclusions are consistent with the results obtained from internationally recognized organizations such as INRIX and TomTom

    How is the construction sector addressing the Circular Economy? Lessons from current practices and perceptions in Argentina

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    The Construction and demolition (C&D) sector mobilise a significant number of resources and at the same time is responsible for a large fraction of waste worldwide (40%-60%). Although, the environmental impact of these by-products is low, waste generated finishes in landfills, is downgraded and because of its volume it has become a priority at different governmental levels. In this context, the Circular Economy (CE) provides a set of strategies to improve efficient use of resources, thus reducing the environmental footprint of C&D. Most academic literature has focused on China, Europe, or the US, but knowledge about CE practices and perceptions in global south countries is scarce. To reduce this knowledge gap, this study focuses on Argentina and explores what are the perceptions, challenges, and opportunities for adopting CE strategies by the C&D sector. To achieve this goal, a survey was developed and distributed with support from the Argentinean Chamber of Construction (CAMARCO), among members of the chamber and other C&D relevant networks. The survey was carried out in the Autumn of 2021 and 88 C&D firms representing different size, longevity and business cycle responded. The results of the survey show that most of surveyed firms are trying to engage with the concept of CE. Secondly, a lack of digitalisation and information are seen as important barriers to transition to CE. Finally, policy makers should focus on providing financial and tax incentives to secure a better environmental future

    Bead, Hoop, and Spring as a Classical Spontaneous Symmetry Breaking Problem

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    We describe a simple mechanical system that involves Spontaneous Symmetry Breaking. The system consists of two beads constrained to slide along a hoop and attached each other through a spring. When the hoop rotates about a fixed axis, the spring-beads system will change its equilibrium position as a function of the angular velocity. The system shows two different regions of symmetry separated by a critical point analogous to a second order transition. The competitive balance between the rotational diynamics and the interaction of the spring causes an Spontaneous Symmetry Breaking just as the balance between temperature and the spin interaction causes a transition in a ferromagnetic system. In addition, the gravitational potential act as an external force that causes explicit symmetry breaking and a feature of first-order transition. Near the transition point, the system exhibits a universal critical behavior where the changes of the parameter of order is described by the critical exponent beta =1/2 and the susceptibility by gamma =1. We also found a chaotic behavior near the critical point. Through a demostrative device we perform some qualitative observations that describe important features of the system.Comment: 7 pages, 2 tables, 30 figures, LaTeX2

    Iron-enriched diet contributes to early onset of osteoporotic phenotype in a mouse model of hereditary hemochromatosis

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    Osteoporosis is associated with chronic iron overload secondary to hereditary hemochromatosis (HH), but the causative mechanisms are incompletely understood. The main objective of this study was to investigate the role of dietary iron on osteoporosis, using as biological model the Hfe-KO mice, which have a systemic iron overload. We showed that these mice show an increased susceptibility for developing a bone loss phenotype compared to WT mice, which can be exacerbated by an iron rich diet. The dietary iron overload caused an increase in inflammation and iron incorporation within the trabecular bone in both WT and Hfe-KO mice. However, the osteoporotic phenotype was only evident in Hfe-KO mice fed the iron-enriched diet. This appeared to result from an imbalance between bone formation and bone resorption driven by iron toxicity associated to Hfe-KO and confirmed by a decrease in bone microarchitecture parameters (identified by micro-CT) and osteoblast number. These findings were supported by the observed downregulation of bone metabolism markers and upregulation of ferritin heavy polypeptide 1 (Fth1) and transferrin receptor-1 (Tfrc), which are associated with iron toxicity and bone loss phenotype. In WT mice the iron rich diet was not enough to promote a bone loss phenotype, essentially due to the concomitant depression of bone resorption observed in those animals. In conclusion the dietary challenge influences the development of osteoporosis in the HH mice model thus suggesting that the iron content in the diet may influence the osteoporotic phenotype in systemic iron overload conditions.National Funds through Foundation for Science and Technology (FCT) Norte-01-0145-FEDER-000012 Portuguese Foundation for Science and Technology (FCT) SFRH/BD/77056/2011 European Regional Development Fund (FEDER) Norte-01-0145-FEDER-000012info:eu-repo/semantics/publishedVersio

    La velocidad del sistema δ Librae

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    In order to resolve the problem of the difference in the system of δ Librae as found when comparing observations made at Allegheny and at Michigan, all the available material, including the Mount Wilson material secured a few years ago and analyzed by two of the authors (J. Sahade and A .Hernández), was measured with the Grant line spectrum comparator of the Department of Astronomy of the Indiana University. When the measurements were reduced (they were made on only one direction of the carriage) it was found that there were systematic differences between the velocities from diffuse and from sharp lines. The latter are in keeping with the velocities obtained with the conventional type of comparators. The preliminary analysis of the results that are consistent suggest that the announced difference in the system velocity at two epochs has no significance and resulted only from the original method of measurement and reduction.Asociación Argentina de Astronomí
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